1. Technical Field
The present invention relates to waveguide manufacturing in general, and in particular to a method for integrating multiple layers of waveguides having uniform dielectric film thickness surrounding each waveguide.
2. Description of Related Art
Theoretically speaking, multiple waveguides can be stacked on top of each other with a thick dielectric inserted between each waveguide by using conventional complementary-metal oxide semiconductor (CMOS) back-end-of-line processing. It is important to have a uniform dielectric around each waveguide within the waveguide stack because transmission power loss can be minimized.
However, complications arise when trying to couple all the waveguide layers in a specific location and not in others. The difficulty stems from the lack of good techniques for providing sufficient etch stops and chemical mechanical polish stops. Consequently, it would be desirable to provide an improved method for manufacturing multiple layers of waveguides having uniform dielectric film thickness surrounding each of the waveguides.